Shirt collar



FIG. 1 shows a front view of a shirt collar.

FIG. 2 shows a rear view thereof.

FIG. 3 shows a side view thereof, the opposite side being a mirror image; and,

FIG. 4 shows a top view thereof.

The broken lines shown in the drawings illustrate portions of a shirt, tie, and mannequin, and form no part of the claimed design. 

CLAIM The ornamental design for the shirt collar, as shown and described. 